by smk-ka: Regression: Fixed not being able to enable either Mime Mail or PHPMailer for e-mail delivery.

by smk-ka: Disabling the module now resets the smtp_library and mimemail_engine variables, to avoid a WSOD.

#499824, #551004 by smk-ka: Added support for PHPMailer's exception handling to avoid dumping errors to the browser (since 5.0.0).

by sun: Simplified settings form (UX).
by smk-ka: Fixed improper RFC 822 formatted date (by Mime Mail).
by smk-ka: Fixed empty mail body with Mime Mail.
by smk-ka: Fixed inconsistent linefeeds with Mime Mail.
by smk-ka: Fixed phpmailer_debug_mail not always rerouting.